Botany and Zoology. 83 
of L. 
referred to L. medeoloides, and from which the figure is drawn, 
represent possibly a distinct species. The figure of Z. avenaceum 
- £. A. Ford on the Pelagic fauna of Freshwater Lakes.—A 
translation of Professor Ford’s paper on this subject, from the 
Biologisches Centralblatt, ii, 299, is given in the Annals and 
Magazine of Natural History for October. Its principal points 
are the following: The pelagic, or deep-water fauna of the lakes 
of Europe is throughout very similar in species, and consists, 
fishes excluded, almost wholly of small Entomostracans of the 
ton. Weismann hence regards them as nocturnal animals 
which keep at the extreme limit of light ; but it is better to say 
through the aid of migratory birds (ducks, grebes, gulls, ete.). 
The cause of the differentiation of the pelagic fauna is attributed 
the shore again, The action tends to make them pelagic and 
confine them to that region; and thus “a differentiation takes 
Place by natural selection, until at last, after a certain number of 
in only the wonderfully transparent Pie 
Ww. 
ea exclusively swimming animals, which we kno 
€ speci a 
